34 synonyms for development such as happening, blooming, circumstance, and event. Development is a noun, and its antonyms are decline and stagnation.
Blooming, blossoming, buildout, burgeoning, enlargement, establishment, evolution, expansion, forming, generation, growth, headway, inauguration, initiation, instigation, institution, invention, maturing, origination, progress, spread, and success.
Circumstance, event, happening, incident, issue, occurrence, outcome, phenomenon, situation, turn of events, and upshot.